1. Field of the Invention
The present invention relates to a device and method for detecting a rate of flow especially in the field of oil drilling and more particularly in the field of operations during drilling. In fact, during such operations, it is often necessary to transmit information from the surface to the well bottom, more particularly for actuating or stopping a mechanism.
2. Description of the Prior Art
Conventional techniques make use of an electric cable or send a ball from the surface. The first technique has the major drawback of having an application limited to turbo drilling, for rotation of the string comprising a cable is impossible or at least requires costly adaptation of the drill stem. The use of a ball released in the drill stems interferes little with the use of the drill stems, but some measuring instruments used during drilling, as well as the hole bottom motors and turbines, do not allow this ball to pass.
The prior art may be illustrated by the following documents U.S. Pat. No. 1,635,040, U.S. Pat. No. 3,717,208, DE-A-2 643 996.